headphones Senn hd560s and old Sony receiver sound boomy.

[MinasBB]

As title says, these cans (120 ohms) sound boomy and really bass boosted on my lbt-n455, also all dsp in the receiver is off. 

BUT when I connect them simultaneously (in what I assume is a parallel connection) with a pair of cans (marshall major 3) they sound natural but also still loud as heck, the marshall are 32 ohms btw.

Any input on this? 

[jaslion]

Thats just how these were made. Since it's a stereo stack meant to be used with it's speakers it's giving you the same kind of equalizer it has on the headphones. It was meant to be woofy af after all.

 

You hooking up 2 is just it losing power and thus pushing a bit less hard on the sennheisers.

 

Basically this thing wasn't meant for what you want from it. Unless you can get into it's equalizer there is little to do about it.

 

That was also the reason this was a more budget set.

[rice guru]

do the 560s sound boomy with any other source?

[Spuriae]

I took a look at the schematics in the service manual for the lbt-n455 and found this:

The headphone output is designed with 440Ω of output impedance.

 

High output impedance sources tend to produce a bass boost in dynamic headphones, as the headphones' own drivers have higher impedances in the bass frequencies. This chart is taken from diyaudioheaven's review of the HD560S. The red line is the headphones' frequency response normally; the green line is the frequency response when the headphones are connected to a 120Ω source.

 

Given the ~2.5dB bass boost from a 120Ω source, the 440Ω output on the lbt-n455 should produce a ~4.5dB bass boost in the HD560S.

 

When you connect the 32Ω headphones in parallel, the effective output impedance that the HD560S "sees" is 440Ω||32Ω, or ~30Ω. This drops the impedance-based bass boost to less than 1dB.

 

[rice guru]

2 hours ago, Nimrodor said:

I took a look at the schematics in the service manual for the lbt-n455 and found this:

The headphone output is designed with 440Ω of output impedance.

 

High output impedance sources tend to produce a bass boost in dynamic headphones, as the headphones' own drivers have higher impedances in the bass frequencies. This chart is taken from diyaudioheaven's review of the HD560S. The red line is the headphones' frequency response normally; the green line is the frequency response when the headphones are connected to a 120Ω source.

 

Given the ~2.5dB bass boost from a 120Ω source, the 440Ω output on the lbt-n455 should produce a ~4.5dB bass boost in the HD560S.

 

When you connect the 32Ω headphones in parallel, the effective output impedance that the HD560S "sees" is 440Ω||32Ω, or ~30Ω. This drops the impedance-based bass boost to less than 1dB.

 

Holy shit 440 ohm is insane lol. or is that a typo cause no headphones would sound as it should on that impedance output

[Psittac]

Might be better to run them with onboard audio.  As @Nimrodor said it has a high output impedance but that's about all I understand, I just know that's a bad thing lol

[rice guru]

10 minutes ago, Psittac said:

Might be better to run them with onboard audio.  As @Nimrodor said it has a high output impedance but that's about all I understand, I just know that's a bad thing lol

High output impedance when not used ina properlm ratio of at least 1/8 1 being output impedance 8 being input impedance you can get away with lower but 1/8 is my personal rule. It will affect the sound signature of a headphone a lot often noticable in the bass regions often making it sound boomier looser but sometimes anemic. This is why with most otl tube amps it's Important to use higher impedance headphones otherwise it's not just the tubes affecting the sound of the headphones

[Spuriae]

2 hours ago, rice guru said:

Holy shit 440 ohm is insane lol. or is that a typo cause no headphones would sound as it should on that impedance output

It's common on these old receivers for there to not be a true headphone output, and instead just have the speaker output also feed to the headphone output, behind a large resistor to reduce the risk of damaging the headphones.

 

Here's the schematic zoomed out a bit. HP-L (the headphone output) and MAIN-L (the speaker output) share the same amplifier.